SnowWolf said:
found post #316683 but that's not quite right.
kodardragon has drawn some pictures of a dragon character with a happy harem of lionesses, but none of those are like you say. (they are really cute though)

the harem tag has a lot of pictures, though they're a bit of a mess and I don't think I see anything under equine_penis harem that looks right.

collaborative_fellatio equine_penis might have you something. (remember you can always -mlp if you are having pony troubles)

That picture you found actually was what spurred the memory for me, so I already knew about that one. x3

They weren't actually doing anything to the cock aside from touching with their hands. I think one of them was playing with his balls? I hate having a faulty memory when it comes to these things.

I'm worried that the one I'm recalling is lost to the annals of time, if it even existed at all.